I have two 1.8Ghz T42s in great condition that I was hoping to use with the upcoming Windows 8, but then I discovered that CPUs without PAE (Physical Address Extension) and the NX/XD bit (Execute Disable Bit) are not supported anymore!

I believe that both my T42s have Pentium M Dothans (SL7EN) CPUs which unfortunately don't support PAE or NX/XD. HOWEVER, I do know that there are a few 400MHz FSB Pentium M Dothans that should support these features plus all the later 533 MHz FSB, C0 stepping Pentium M CPUs. Also, The 2.1GHz Pentium M 765 SL7V3 should support the necessary features.

The GPU in my T42s are the 64MB ATI Mobility Radeon 9600, but that is the "least" of my worries.

I have read that CPUs are now required to have PAE and NX/XD to be able to install "Windows 8" and the old Pentium Ms found in the T42-series support PAE according to Intels website, but only a few of the old Pentium Ms support the NX/XD bit.

Since the NX/XD bit cannot be enabled in the T42 BIOS, Microsoft has provided the following potential workaround:

Download the Windows 8 Release Candidate ISO and burn it to a DVD or create a bootable USB flash drive. Boot from the media that you created. If your CPU does not support NX you will see a code 5D bluescreen before setup starts.

This workaround may succeed because Windows contains two installers: the end user installer (setup.exe at the root of the Windows DVD) and the commercial installer (setup.exe found in the \sources directory of the Windows DVD). The commercial installer runs when the PC is booted from DVD/USB media and does not perform the NX/SSE2 checks and attempts to enable NX/SSE2 on supported systems.

I am hoping that someone will try to install "Windows 8 RC" on a T42 maybe equipped with a SL7V3 or a SL8QZ CPU - or maybe even a later 533FSB CPU taken from T43-series.

I have T42's. I have purchased a dothan 750 ($3.95) to try it experimentally in my T42's. The 7x5 Dothans REALLY DO NOT have the NX feature - it was missing from the VLSI design! You need the NX memory-protection feature - it is heavily used by the Win8 kernel for security reasons and to verify that the CPU supports SSE2 !! (7x5's support SSE2 but not NX!)

If this works o.k. on my Dothan 750, I will buy 780's which should run at the equivalent of about 1.7 Ghz (= 2.26 * 400/533). I am not going to depend upon overclocking to run this OS. Dothan 780's as "pulls" from other laptops cost about $40-$50/ea. Total OS upgrade cost = ~$80-$90.

The ATI 9600 / FireGL-T2 (same guts) was a best-selling graphics card from ~2002 until 2005 or 2006, I expect it will be supported for another 3-5 years by ALL operating systems.

Yes - for one processor *only* it is compatible - that is the Intel M 765 SL7V3 Dothan.

Why only this last processor of the 400 MHz FSB series (715, 725, 735, 745, and 755) has 32-bit PAE, NX/XD, and SSE2 enabled, is beyond me.

As a partial trial, I dropped in the 533 MHz FSB 780 SL7VB realizing that the higher FSB speed would de-rate the whole CPU in being forced back to 400 Mz. The "test bed" had the ATI Radeon 7500 GPU, 2 GB of high-quality RAM, 100 GB 7200 RPM drive (Travelstar)

In actuality, the T-42 did run with 780 and was "as slow as molasses". The BIOS is clearly not written for this type of situation. In trying to use the Win 8 RTM Upgrade Assistant, the system was failed as the hardware was too slow.

I then swapped that for the 765 and passed the compatibility tests quite quickly (I'm guessing several minutes).

So... final answer - only the last of the (715, 725, ... 765) series works and appears to be as fast, if not faster, than XP.

No, I have not formally benchmarked it. I did run CPU-Z and the readout appears as expected. I also ran CPU-ID's HW Monitor and CPU temp using Arctic Silver 5 thermal paste was 33 - 37 degrees C / 91 - 97 degrees F.

Hi! I tested a few CPU's on two different machines, a T42p and a R50p (R50p have USB 2.0).

With both CPU's (740 and 750) with 533 MHz FSB, Windows 8.1 has installed without any problems but the clock was downgraded (FSB 400 MHz). For SpeedStep I used RMClock Utility 2.35, even for voltage adjustment (it lowering temperature in idle). Without RMClock the cpu's frequency was not raised (only 6x multiplicator). With any other CPU with 400 MHz FSB has no troubles with Intel SpeedStep in Windows 7, but no success with installing a new or running an already installed Windows 8.

I have a lot of 400 MHz CPU's, even a 745 and a 765 for which Intel says thath both support PAE and NX http://ark.intel.com/products/27596/Int ... 00-MHz-FSB . So, I'm still in search of solutions, but I think that without any mod BIOS or windows patch, a SL7V3 or a SL7EN (if I remember) will not run/install Windows 8. I already have the last BIOS version. I will test the SL7V3 on a FSB 533 MHz Fujitsu Laptop to verify if truly had activated PAE and NX, then I will try to mod original BIOS with some BIOS ModTools for .img file to show in BIOS menu NX settings. Wish me luck!

Hi there, instead of worrying about whether CPUs support features X Y or Z there is a patcher that has been made to disable the checks, supposedly bypassing the NX check is a relatively harmless tweak.

I just got a T420 in good condition for under $100 on Craigslist. I loved the old T4x series computers but their day has passed - when you consider all of the issues with this model (display backlights going out, graphics chips parting company with the motherboard, etc) maybe it's time to bite the bullet and bury the old girl!

I just got a T420 in good condition for under $100 on Craigslist. I loved the old T4x series computers but their day has passed - when you consider all of the issues with this model (display backlights going out, graphics chips parting company with the motherboard, etc) maybe it's time to bite the bullet and bury the old girl!